US3645148A - Skew axis gearing - Google Patents

Skew axis gearing Download PDF

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Publication number
US3645148A
US3645148A US46402A US3645148DA US3645148A US 3645148 A US3645148 A US 3645148A US 46402 A US46402 A US 46402A US 3645148D A US3645148D A US 3645148DA US 3645148 A US3645148 A US 3645148A
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Prior art keywords
gear
pinion
axis
gearing
face
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US46402A
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Ernst Schrempp
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Pitney Bowes Inc
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Pitney Bowes Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H1/00—Toothed gearings for conveying rotary motion
    • F16H1/02—Toothed gearings for conveying rotary motion without gears having orbital motion
    • F16H1/04—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members
    • F16H1/12—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes
    • F16H1/14—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes comprising conical gears only
    • F16H1/145—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes comprising conical gears only with offset axes, e.g. hypoïd gearings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T74/00—Machine element or mechanism
    • Y10T74/19—Gearing
    • Y10T74/19642—Directly cooperating gears
    • Y10T74/19688—Bevel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T74/00—Machine element or mechanism
    • Y10T74/19—Gearing
    • Y10T74/19642—Directly cooperating gears
    • Y10T74/19698—Spiral
    • Y10T74/19828—Worm

Definitions

  • the disclosed k axis gearing includes a face gaar which is [51] llll. C1 ..Fl611 1/14, F1611 1/16, F1611 1/20 driven by a cylindrical pinion or worm gear having a constant 01 Search X lead throughout length.
  • the pinion teeth are of p I zoidal cross section and are symmetrical to a bisecting axis [56] Re'eremes cued perpendicular to the pinion axis.
  • Skew axis gearing sometimes termed hypoid gearing, refers to a pinion and face gear set wherein the gear axes are both nonparallel and nonintersecting. Gearing of this type is advantageous in applications calling for fairly high gear ratios with stringent space limitations.
  • the gear set can be designed to transmit fairly high power with virtually no backlash.
  • skew axis gear sets have employed face gears molded of a suitable plastic, such as Delrin nylon, etc.
  • An additional object is to provide skew axis gearing of the above character which is inexpensive to manufacture using conventional techniques and equipment.
  • a further object is to provide skew axis gearing of the above character which is capable of transmitting substantial power over a long operating life and is conducive to large reduction ratios.
  • Another object is to provide skew axis gearing of the above character which is compact in size and thus capable of meeting stringent space limitations.
  • I provide skew axis gearing in which the pinion or wonn gear is of an uniquely simplified design as compared to prior art skew axis pinions.
  • the skew axis gearing of my invention is significantly less expensive to manufacture.
  • the skew axis pinion gear does not have a tapered configuration, but in fact is essentially perfectly cylindrical.
  • the pinion gear is essentially a worm or screw of constant lead.
  • the thread or tooth profile of the pinion is trapezoidal in cross section and is symmetrical about a bisecting axis perpendicular to the pinion axis. That is, the tooth profile has equal pressure angles. This greatly simplifies manufacture procedures using convention techniques and procedures well known in the art.
  • Simplification of the pinion design afforded by my invention also results in simplification of the face gear design required for conjugate action.
  • the face gear may be formed of plastic using a relatively inexpensive mold design.
  • the instant skew axis gearing is extremely efficient, quiet, and capable of long operating life.
  • the skew axis gearing of my invention due to the equal pressure angles, is antioverhauling in the sense that when power is removed from the pinion, the face gear cannot effectively overtake and drive the pinion.
  • the pinion effectively acts as a brake on the face gear shaft, the output shaft, when the pinion ceases to be driven. In many applications this is an essential feature and by using my design, separate output shaft braking provisions are unnecessary.
  • FIG. 1 is a top plan view of a skew axis gear set constructed according to a preferred embodiment of my invention.
  • FIG. 2 is a fragmentary sectional view showing the tooth or thread profile of the pinion gear of FIG. 1.
  • the skew axis gearing of the present invention comprises a face gear 12 secured on an output shaft 14 and a pinion or worm gear 16 integrally formed or otherwise secured on an input shaft 18.
  • the input shaft is positioned at right angles to the output shaft and is offset therefrom so that the shafts do not intersect.
  • the thread or threads (helical teeth) 20 of the pinion 16 mesh with teeth 22 of the face gear 12 as the pinion drives the face gear. It is seen that by virtue of the skew axis orientation, there are multiple teeth in meshing interengagement enabling the gear set to transmit substantial power.
  • the pinion tooth or thread profile seen in the cross section of FIG. 2 is trapezoidal and is symmetrical about a bisecting axis 23 perpendicular to the pinion axis 24.
  • the pressure angles 26 of the pinion 16 are equal and are preferably each established at the conventional hob angle of 14% for ease of fabrication. Other hob angles may be employed, however.
  • the pinion is the primary element of the skew axis gear set and once it is designed the face gear design can be generated using conventional hobbing techniques.
  • the pinion is designed in accordance with the following formula:
  • L equals the pinion thread lead.
  • 0 is the magnitude of offset of the pinion axis 24 from the face gear horizontal axis 28 measured along the gear vertical axis 30 which is perpendicular to the pinion axis (FIG. 1).
  • R equals the desired gear or speed ratio or the ratio of the number of gear teeth 22 to the number of pinion threads 20. I have found that I can readily achieve reduction ratios of 50:1. I have also found that application of the above formula results in gear teeth after hobbing which are free of inactive fillets or undercuts. Thus the resulting face gear is of optimum design and strength for a given offset 0 and gear ratio R. Consequently, the face gear may be and preferably is molded in a suitable plastic such as Delrin.
  • the skew axis gearing of my invention is exceptionally efficient in the driving direction, 70-75 percent for reduction ratios as high as 50:], but is relatively inefficient in the driven direction.
  • the disclosed skew axis gear due to the equal pressure angles, is essentially unidirectional.
  • This apparent drawback is highly advantageous in certain applications where it is desired that the face gear be effectively incapable of overhauling or overtaking the pinion and thereby act as the driving member instead of the driven member.
  • the gearing of my invention when driving power is removed from the pinion, it then effectively acts as a brake on the face gear.
  • use of the disclosed gearing in some applications can eliminate the need for a separate brake to inhibit further rotation of the gear shaft 14 after driving power has been removed from the pinion shaft 18.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Gears, Cams (AREA)
  • Gear Transmission (AREA)

Abstract

The disclosed skew axis gearing includes a face gear which is driven by a cylindrical pinion or worm gear having a constant lead throughout its axial length. The pinion teeth are of trapezoidal cross section and are symmetrical to a bisecting axis perpendicular to the pinion axis. Thus the pinion teeth have equal pressure angles.

Description

llnfitefl Slams Patent Schrempp 1. Feb. 29, 1972 [54] SKEW AXIS GEARHNG 3,038,346 6/1962 MacFarland ..74/425 X [72] Inventor: Ernst schrempp Norwalk' Conn 2,810,305 10/1957 Bnnza et al. ..74/423 UX [73] Assignee: Pitney-Bowes, Inc, Stamford, Conn. Primary ExaminerLeonard H. Gerin AttorneyWilliam D. Soltow, Jr., Albert W. Scribner, Martin [22] June 1970 D. Wittstein and Louis A. Tirelli [21] Appl. N0.: 46,402
i ABSTRACT [52] US. Cl... ..74/423, 74/425 The disclosed k axis gearing includes a face gaar which is [51] llll. C1 ..Fl611 1/14, F1611 1/16, F1611 1/20 driven by a cylindrical pinion or worm gear having a constant 01 Search X lead throughout length. The pinion teeth are of p I zoidal cross section and are symmetrical to a bisecting axis [56] Re'eremes cued perpendicular to the pinion axis. Thus the pinion teeth have UNITED STATES PATENTS equal Press"re angles- 3, 224,290 l2/ 1 965 Polydoris ..74/424.5 3 Claims, 2 Drawing Figures 1(0 r Q l7 a PAIENTDFEB29 I972 3, 45,14
INVENTOR. ERNST SCH QEMDD BY WM um ATTORNEY SKEW AXIS GEARING BACKGROUND AND OBJECTS OF THE INVENTION Skew axis gearing, sometimes termed hypoid gearing, refers to a pinion and face gear set wherein the gear axes are both nonparallel and nonintersecting. Gearing of this type is advantageous in applications calling for fairly high gear ratios with stringent space limitations. The gear set can be designed to transmit fairly high power with virtually no backlash. Recently, such skew axis gear sets have employed face gears molded of a suitable plastic, such as Delrin nylon, etc.
Heretofore, it has been considered necessary to give the gears a peculiar shape and/or tooth or thread profile in order to achieve sufficient as well as proper tooth engagement to transmit substantial power with minimum wear. Thus, crown or bevel gears have been proposed. The pinion or worm, in turn, has been formed with varying degrees of taper. Also, the tooth profiles have been given a variety of shapes calculated to transmit substantial power and to satisfy other requirements. All of these proposals have led to skew axis gear designs which are difficult and expensive to manufacture.
It is accordingly a general object of my invention to provide improved skew axis gearing of simplified design.
An additional object is to provide skew axis gearing of the above character which is inexpensive to manufacture using conventional techniques and equipment.
A further object is to provide skew axis gearing of the above character which is capable of transmitting substantial power over a long operating life and is conducive to large reduction ratios.
Another object is to provide skew axis gearing of the above character which is compact in size and thus capable of meeting stringent space limitations.
Other objects of my invention will in part be. obvious and will in part appear hereinafter.
SUMMARY OF THE INVENTION In accordance with the present invention, I provide skew axis gearing in which the pinion or wonn gear is of an uniquely simplified design as compared to prior art skew axis pinions. As a consequence, the skew axis gearing of my invention is significantly less expensive to manufacture.
More specifically, the skew axis pinion gear does not have a tapered configuration, but in fact is essentially perfectly cylindrical. Thus, the pinion gear is essentially a worm or screw of constant lead. Moreover, the thread or tooth profile of the pinion is trapezoidal in cross section and is symmetrical about a bisecting axis perpendicular to the pinion axis. That is, the tooth profile has equal pressure angles. This greatly simplifies manufacture procedures using convention techniques and procedures well known in the art.
Simplification of the pinion design afforded by my invention also results in simplification of the face gear design required for conjugate action. As a result the face gear may be formed of plastic using a relatively inexpensive mold design.
I have found that the skew axis gearing of my invention is conductive to relatively large reduction ratios; for example 50:1, unlike typical prior art designs. Power transmission capabilities are found to be considerable, particularly in view of the compactness and tooth size of the subject gearing.
Moreover, the instant skew axis gearing is extremely efficient, quiet, and capable of long operating life. As an added benefit, the skew axis gearing of my invention, due to the equal pressure angles, is antioverhauling in the sense that when power is removed from the pinion, the face gear cannot effectively overtake and drive the pinion. Thus, the pinion effectively acts as a brake on the face gear shaft, the output shaft, when the pinion ceases to be driven. In many applications this is an essential feature and by using my design, separate output shaft braking provisions are unnecessary.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:
FIG. 1 is a top plan view of a skew axis gear set constructed according to a preferred embodiment of my invention; and
FIG. 2 is a fragmentary sectional view showing the tooth or thread profile of the pinion gear of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, the skew axis gearing of the present invention, generally indicated at 10 in FIG. 1, comprises a face gear 12 secured on an output shaft 14 and a pinion or worm gear 16 integrally formed or otherwise secured on an input shaft 18. The input shaft is positioned at right angles to the output shaft and is offset therefrom so that the shafts do not intersect. The thread or threads (helical teeth) 20 of the pinion 16 mesh with teeth 22 of the face gear 12 as the pinion drives the face gear. It is seen that by virtue of the skew axis orientation, there are multiple teeth in meshing interengagement enabling the gear set to transmit substantial power.
The pinion tooth or thread profile seen in the cross section of FIG. 2 is trapezoidal and is symmetrical about a bisecting axis 23 perpendicular to the pinion axis 24. The pressure angles 26 of the pinion 16 are equal and are preferably each established at the conventional hob angle of 14% for ease of fabrication. Other hob angles may be employed, however.
The pinion is the primary element of the skew axis gear set and once it is designed the face gear design can be generated using conventional hobbing techniques. In accordance with my invention, the pinion is designed in accordance with the following formula:
where L equals the pinion thread lead. 0 is the magnitude of offset of the pinion axis 24 from the face gear horizontal axis 28 measured along the gear vertical axis 30 which is perpendicular to the pinion axis (FIG. 1). R equals the desired gear or speed ratio or the ratio of the number of gear teeth 22 to the number of pinion threads 20. I have found that I can readily achieve reduction ratios of 50:1. I have also found that application of the above formula results in gear teeth after hobbing which are free of inactive fillets or undercuts. Thus the resulting face gear is of optimum design and strength for a given offset 0 and gear ratio R. Consequently, the face gear may be and preferably is molded in a suitable plastic such as Delrin.
The skew axis gearing of my invention is exceptionally efficient in the driving direction, 70-75 percent for reduction ratios as high as 50:], but is relatively inefficient in the driven direction. Thus the disclosed skew axis gear, due to the equal pressure angles, is essentially unidirectional. This apparent drawback is highly advantageous in certain applications where it is desired that the face gear be effectively incapable of overhauling or overtaking the pinion and thereby act as the driving member instead of the driven member. Thus in the gearing of my invention, when driving power is removed from the pinion, it then effectively acts as a brake on the face gear. Thus, use of the disclosed gearing in some applications can eliminate the need for a separate brake to inhibit further rotation of the gear shaft 14 after driving power has been removed from the pinion shaft 18.
. It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are tifi l ciently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
Having described my invention, what I claim as new and IFZnO/R desired to secure by Letters Patent is: where equals the offset of the pinion gear axis from the 1 Skew xi gearing co p i i g, in Combination; face gear axis measured along an axis perpendicular to a face fi both gear axes, and R equals the gear ratio or the ratio B. a cylindrical pinion gear in meshing engagement with 5 of the number of face gear teeth to the number f Said face s n pinion threads.
C. at least one helical thread of constant lead formed on 2. The Skew axis gearing defined in claim I, wherein the said pinion gear, said thread having 1. a trapezoidal profile which is symmetrical about a bisecting axis perpendicular to the axis of said pinion l0 gear to provide equal pressure angles, and
2. a lead determined in accordance with the formula:
thread pressure angles are each 14%".
3. The skew axis gearing defined in claim 1, wherein said face gear is formed of molded plastic.
1|K i t lOlOZS 0165

Claims (4)

1. Skew axis gearing comprising, in combination; A. a face gear; B. a cylindrical pinion gear in meshing engagement with said face gear; and C. at least one helical thread of constant lead formed on said pinion gear, said thread having 1. a trapezoidal profile which is symmetrical about a bisecting axis perpendicular to the axis of said pinion gear to provide equal pressure angles, and 2. a lead determined in accordance with the formula: L 2 pi O/R where O equals the offset of the pinion gear axis from the face gear axis measured along an axis perpendicular to both gear axes, and R equals the gear ratio or the ratio of the number of face gear teeth to the number of pinion threads.
2. a lead determined in accordance with the formula: L 2 pi O/R where O equals the offset of the pinion gear axis from the face gear axis measured along an axis perpendicular to both gear axes, and R equals the gear ratio or the ratio of the number of face gear teeth to the number of pinion threads.
2. The skew axis gearing defined in claim 1, wherein the thread pressure angles are each 14 1/2 *.
3. The skew axis gearing defined in claim 1, wherein said face gear is formed of molded plastic.
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3768326A (en) * 1971-12-16 1973-10-30 V Goldfarb Orthogonal skew-axis gearing
FR2367952A1 (en) * 1976-10-16 1978-05-12 Bosch Gmbh Robert CONTROL UNIT FOR AUXILIARY ELECTRICAL DEVICES OF MOTOR VEHICLES
WO2001071220A1 (en) * 2000-03-20 2001-09-27 Sew-Eurodrive Gmbh & Co. Modular transmission system
US20020078777A1 (en) * 2000-12-27 2002-06-27 Witucki David E. Gear assembly
US20030101837A1 (en) * 2000-03-31 2003-06-05 John Abrahamsen Actuator
US20060219036A1 (en) * 2003-04-25 2006-10-05 Thk Co., Ltd., Hypoid gear device
US20100237216A1 (en) * 2009-03-17 2010-09-23 Mircea Napau Power seat height adjuster mechanism
US20110132117A1 (en) * 2009-12-09 2011-06-09 John Christian Yaeger Variable torque transmitting device
DE102017211803A1 (en) * 2017-07-11 2019-01-17 Zf Friedrichshafen Ag High-ratio bevel gearbox
WO2019101432A1 (en) * 2017-11-23 2019-05-31 Robert Bosch Gmbh Drive transmission for a steering mechanism

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2810305A (en) * 1956-04-27 1957-10-22 Illinois Tool Works Multi-speed power unit
US3038346A (en) * 1960-11-28 1962-06-12 Illinois Tool Works Tuning device
US3224290A (en) * 1962-03-28 1965-12-21 Polydoris Nicholas George Drive mechanism

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2810305A (en) * 1956-04-27 1957-10-22 Illinois Tool Works Multi-speed power unit
US3038346A (en) * 1960-11-28 1962-06-12 Illinois Tool Works Tuning device
US3224290A (en) * 1962-03-28 1965-12-21 Polydoris Nicholas George Drive mechanism

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3768326A (en) * 1971-12-16 1973-10-30 V Goldfarb Orthogonal skew-axis gearing
FR2367952A1 (en) * 1976-10-16 1978-05-12 Bosch Gmbh Robert CONTROL UNIT FOR AUXILIARY ELECTRICAL DEVICES OF MOTOR VEHICLES
US8578817B2 (en) 2000-03-20 2013-11-12 Sew-Eurodrive Gmbh & Co. Modular transmission system
WO2001071220A1 (en) * 2000-03-20 2001-09-27 Sew-Eurodrive Gmbh & Co. Modular transmission system
US20080172877A1 (en) * 2000-03-20 2008-07-24 Sew-Eurodrive Gmbh & Co. Modular transmission system
US7707721B2 (en) 2000-03-20 2010-05-04 Sew-Eurodrive Gmbh & Co. Modular transmission system
US20030101837A1 (en) * 2000-03-31 2003-06-05 John Abrahamsen Actuator
US6770006B2 (en) * 2000-03-31 2004-08-03 Linak A/S Actuator
US20020078777A1 (en) * 2000-12-27 2002-06-27 Witucki David E. Gear assembly
US20060219036A1 (en) * 2003-04-25 2006-10-05 Thk Co., Ltd., Hypoid gear device
US8556762B2 (en) 2009-03-17 2013-10-15 Crh North America, Inc. Power seat height adjuster mechanism
US20100237216A1 (en) * 2009-03-17 2010-09-23 Mircea Napau Power seat height adjuster mechanism
US20110132117A1 (en) * 2009-12-09 2011-06-09 John Christian Yaeger Variable torque transmitting device
DE102017211803A1 (en) * 2017-07-11 2019-01-17 Zf Friedrichshafen Ag High-ratio bevel gearbox
WO2019101432A1 (en) * 2017-11-23 2019-05-31 Robert Bosch Gmbh Drive transmission for a steering mechanism

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